Make sure you have entered the correct prefix. For example Japanese transistors often omit the leading "2S" (C1384 being 2SC1384, A1015 being 2SA1015).

Parts with many different parameters (such as crystals, or capacitors) often do not have individual datasheets. They have part numbering guides. For example a philips capacitor 222231190112 may be found by searching for "2222 capacitor philips" or "2222 capacitors philips guide".